Lead alloy, particularly for cable sheathings



Patented Oct. 28, 1930 UNITED STATES PATENT OFFICE MARTIN THIELE BS, OF STOCKHOLM, SWEDEN ZEAD ALLOY, PARTICULARLY FOR CABLE SHEATHINGS No Drawing. Application filed March 15, 1928, Serial K0. 262,026, and in'sweden larch 18, 1928.

Sheathings for cables, especially for communication purposes, are generally made ,from lead, either alone or in alloy with other I substances which serve .t o give the lead a certain hardness and make the sheathing suf ficiently resistant against chemical corrosion and against so-called intra-crystalline' corrosion caused by vibrations. As hardening substance, tin in a quantity of about 13% has been used since long time, and later on also antimony .in a quantity of about 1% was used. It has also been proposed to employ magnesium in small quantities. The advantage-of using antimony or magnesium lies primarily in the fact that the alloys thus formed will be substantially cheaper than lead-tin alloys; furthenan alloy of lead-and s antimony ls for instance stated to be more-- resist-ant against intra-crystalline corrosion than the lead-tin alloy.

My investigations have however proved that the production of a suitable sheathing from lead-antimony alloy meets with certain difiiculties, so that such a sheathing often becomes uneven and brittle so as to burst- .in bending. A close investigation ofthe fracture shows sometimes a finely crystalline aspect and a Stratified structure ofthe material. These circumstances are supposed to be due partly to an inappropriate distribution of the antimony in the lead, partly toan in-' appropriate mechanical or thermical treatment of the alloy in'course of production,

and partly also to impurities'present.

I have further found that an alloy which is very suitable for the aforesaid purpose is obtained by adding to the lead-antimony-alby a small quantityof bismuth which acts to increase the solubility of antimony in lead. Ihave found that such an alloy pus--- ses'ses a' greater uniformity,- stability, and tenacity than the usual lead-antimony alloy.- The quantity of bismuth added should however be very" small, generally not more than two tenths of a percent, although under certain circumstances appropriate sheathings can be made from-alloys holding a hi her percentage of bismuth (up to aboutto'nealf percent),

The addition of bismuthcan be made-in used in other cases where corresipondm'g me- I chanical properties are require I claim as my invention \1. An alloy consisting of about 99% of lead, 1% of antimony and a small quantity of bismuth.

'2. An alloy consisting of between 98 and 99% of lead, about 1% of antimony and one half percent or less of bismuth.

In testimony whereof I have signed my name to this specification.

" MARTIN THIELEBS. 

